As more and more data is being made available by FEMA, State Government and Local Governments, specifically high resolution topographic data; two dimensional modeling and requests for two dimensional modeling is becoming more and more prevalent.
Currently there are numerous 2D models that are becoming more mainstream within the industry including Flo-2d, TuFlow, GeoHECRAS, River2d etc. One of the newest programs to feature two dimensional modeling the is US Army Corps of Engineers program HEC-RAS. The most recent edition now includes two dimensional modeling capabilities which can be coupled with the standard cross sectional one dimensional analysis.
The following paper discusses the capabilities of HEC-RAS and provides some guidance on how to set up these projects: http://www.hec.usace.army.mil/misc/files/ras/Combined_1D_and_2D_Modeling_with_HEC-RAS.pdf
-Chris McFarland, PE, CFM